Frequently Asked Questions
A Flex Route is an active traffic management system that promotes safety and helps manage rush hour and seasonal traffic congestion by utilizing the median shoulder as a temporary third lane.
MDOT is installing Michigan’s first Flex Route system on US-23 north of Ann Arbor, from M-14 to M-36.
US-23 north of Ann Arbor was selected for Michigan’s first Flex Route because it is an area where rush hour and seasonal traffic congestion is commonplace, the surface needed to be rehabilitated, and the geography and narrow confines of the MDOT right of way made other options prohibitively expensive. The three-hour pulses of heavy traffic during morning (southbound) and evening (northbound) rush hours, and relatively lighter traffic outside of these time blocks, allowed us to right-size the solution to the problem using traffic management technology. Once completed next year, we expect to see an average rush hour drive time reduction of about 20 minutes through this stretch.
The US-23 Flex Route work is expected to be completed by the end of 2017.
The Flex Route temporary lanes will be opened for travel as needed during peak travel periods – typically during the morning commute on southbound lanes and the evening commute on northbound lanes – and when traffic is backed up because of heavy seasonal traffic and other temporary conditions, such as bad weather, traffic incidents or construction.
The Flex Route will be monitored by MDOT’s Statewide Transportation Operations Center (STOC). The STOC is a seven-day-a-week operation that houses dispatchers from MDOT and Michigan State Police. The agencies share resources and information by monitoring traffic sensors, distress calls and video feeds from closed-circuit TV cameras. They also coordinate their efforts with law enforcement agencies and other transportation officials.
Flex Route will be connected to the STOC through the use of expanded intelligent transportation systems (ITS) technology. This will include an intelligent lane control system consisting of overhead signs, cameras, and electronic message boards, which STOC employees will monitor and adjust as needed.
If a traffic condition develops, the STOC will adjust the Flex Route through electronic lane control signs mounted above each lane. These signs will show motorists which lanes are available and provide the recommended speed for the current travel conditions.
Any traffic incidents will be managed with assistance from MDOT’s Freeway Courtesy Patrol (FCP) and several new crash investigation sites that will be strategically located along the corridor.
A large green arrow posted above a widened shoulder (flex lane) will show when that Flex Route is available as a third lane.
A large red X above the widened shoulder (flex lane) will show when that Flex Route is not to be used.
Yellow chevrons will direct motorists to move over or merge to avoid incidents ahead.
Flex Route technology will be considered for highways that frequently experience traffic congestion during peak travel periods.
A 24-hour fix simply is not necessary on corridors that typically experience traffic slowdowns only during regular peak travel periods. It is more cost-effective to adapt the shoulder for use as a temporary third lane than it would be to install a third lane. Employing Flex Route technology enables to achieve more capacity out of the existing infrastructure for less money.
Implementing a Flex Route requires less capital than adding another lane – primarily because it works within the existing infrastructure and doesn’t require the same degree of expansion to implement.
11. Why would a different speed limit be recommended for the Flex Route when there's already one posted for US-23?
A lower recommended speed limit would be posted, for example, if motorists were approaching a traffic incident or other circumstances where slower speeds would promote safer travel, such as inclement weather and slippery roads.
Drivers need to familiarize themselves as to how a Flex Route works; they can start by viewing this brief video. If a driver is uncomfortable driving the Flex Route, MDOT recommends they handle it the same way that drivers should handle most any traffic situation: slow down and stay to the right.
Trained operators in MDOT's STOC will use traffic sensors and real-time video images to monitor travel conditions. This data will enable them to identify any slowdowns, traffic incidents and/or lane blockages ahead.
STOC operators will respond in real time to current travel conditions. For example, when traffic slows to speeds pre-established in guidelines, operators will open or close lanes accordingly. They also will post appropriate safety information to guide motorists, such as lane blockages ahead and recommended speed limits for existing conditions.
Michigan's first Flex Route will provide the communications backbone to support connected autonomous vehicles (CAV) and vehicle-to-infrastructure (V2I) technology.